The bosses of the bailed-out banks Lloyds Banking Group and Royal Bank of Scotland faced calls from MPs today to disclose the number of employees who earn more than them in a move that will fuel demands for routine disclosure of the sums bankers are paid.

Eric Daniels, chief executive of Lloyds, promised to provide the information to the Treasury select committee after revealing that employees below board level were earning more than the £1.1m he received last year. Stephen Hester, his counterpart at RBS, was less willing to provide information about bankers who earned more than his £1.2m.

When asked if he was the highest-paid employee, Daniels said: "That would not be right."

As Daniels did not accept a £2.3m bonus he was awarded last year, four boardroom colleagues took home more than him. One was Helen Weir, who runs the retail banking arm. Sitting beside Daniels at the hearing, Weir faced the humiliation of being accused of not knowing what she paid in bank charges while insisting the average customer paid "less than a cup of coffee a week".

The admission prompted Andrew Tyrie, the Conservative MP who chaired the committee, to sum up the appearance by Lloyds bankers by saying: "The idea that customers know how much they are paying for their current accounts will be met with something of a loss of credulity, particularly given that the group executive director herself didn't know how much she was paying."

In admitting he was not the highest-paid director, Daniels was referring to unnamed bankers outside the boardroom. "We have specialists and as you would expect people who have very specialist skills have a different market comparitor," he said. "We could very easily have people making more than I am."

But he confounded MPs when he insisted he did not know how many employees earned more than him. "I would not venture a guess," Daniels said.

As Lloyds does not have an investment bank, the discovery that bankers below board level are taking home millions may surprise some observers.

RBS, meanwhile, employs 15,000 investment bankers and is accustomed to scrutiny over high pay. But while Hester said he knew the amount paid to the highest-paid employee inside the bank, he would not tell the committee. Even so, he insisted he was "not arguing against" Walker-style disclosure in the UK.

The MPs called the bank bosses to discuss competition in the sector. Hester insisted RBS was able to compete on the high street even though competition rules had been waived to allow Lloyds to rescue HBOS during the banking crisis.

The coalition has set up the independent commission chaired by Sir John Vickers to consider breaking up Lloyds or forcing investment banks to split off from high-street banks.

When asked about the threat of a break-up, Daniels said: "That is a hypothetical question … it is very premature to judge an outcome."

Both banks insisted they were not making profits from overdraft charges, which can be almost 20%, compared with the Bank of England base rate of 0.5%. The Office of Fair Trading has calculated that a third of all fees from current accounts are generated through such charges.

Neither chief executive would say when he felt the government would sell off its shares but Hester said a sale "would be a symbol of Britain's recovery and help with that, and a symbol of RBS's recovery".